It’s always enjoyable building functional art and in this case it’s a Cadillac exhaust system built for a straight up show car. The requirements for this project are:

everything must be 304 stainless steel

everything must be tucked tightly to the underside of the car as it can lay on the ground (has bags)

all welds must be blended and not visible

must be polished

And that’s it! Working with raw materials and getting it to this level of quality takes a considerable amount of time. Building a stainless exhaust alone requires the material to be TIG welded, properly backpurged and with the additional requirement of blending the welds, sanding and the final polishing.

The Cadillac was dropped off with a donor floor pan on it, many mock up parts and a simple primed frame. This allowed a clean slate to allow fitting this 2″ tubing as tight as possible to the underside of the car and snaking it through the rear axle area. First off we unload all our materials to begin!

Second was unloading the car off the flat deck and onto the hoist. We had to get a bit creative as the rolling chassis didn’t have any springs in place and only had wood blocks to keep the wheels from rubbing and the rails from completely dropping to the floor.

Fabrication

This system was built in four separate sections to allow for easy assembly/disassembly. Below are a few photos of the hours of mock up, tacking, welding and blending process.

Take special note at the Kapton tape on the flex section. This is for two purposes, one to protect the woven stainless steel from arcing while tacking/welding and also eliminating snags and potential damage during sanding/polishing.

Since the exhaust is tucked so tight there has to be minimal movement, one mounting location the exhaust will be hard mounted to is this bushing location. First a cardboard template is made and then it is CNC cut on the plasma table, and then welded on. With the CNC cutting the hole is slotted to allow for some wiggle room during installation.

Note the existing hole right just above the rear exhaust tip. That hole was already existing, instead of drilling new holes along the frame that hole was used (along with a necessary one drilled adjacent to it) to allow for securing the rear of the exhaust.

Prepping the rear section for final welding. Kapton tape used to ensure no air is brought inside the tubing during purging, and also to reduce the waste of argon. Kaptop tape has a decent temperature rating, so if it’s close to another weld and gets a bit warm, when it’s removed it doesn’t leave any adhesive behind. This saves time having to clean up adhesive residue and just allows us to get on with welding right away.

Once the welding was completed the tip was polished prior to the hanger being welded on. Once the hanger is installed it is very difficult to polish the pipe, so all the hanger sections have to be pre-polished prior to the hangers being welded on. Then the area is protected and ultimately repolished when the rest of the exhaust system is polished.

And welded on. The hanger was also CNC cut and is slotted to allow for some movement during installation. The hardware threads into two Rivnuts installed on the frame rail.

One last modification. Removing a bit of material and welding in a section to allow the pipe to tuck tight enough under the car to allow it to sit on the ground. Material removal is done with a handheld plasma cutting torch, then the surface is sanded flat and deburred. The hole is then transferred to a piece of paper and then ultimately to a sheet of stainless that is cut by hand in the bandsaw. It is welded on with a taller than normal bead to allow for blending.

Once the system is fully welded and all the hangers are on, then the bulk of blending, sanding and polishing comes into play.

Some of the many many belts that were used to sand and polish the tubing.

A neat trick to share. Spray machinist layout fluid on the tubing in order to see where you have sanded and where there may be small divots in the tubing (you can see one easily in this picture). the layout fluid is essentially like very thin quick drying spray paint. However unlike spray paint you can take it off with a remover as well, in this case it was just sanded off. It’s thin enough that it doesn’t clog the belt even at the finer grit levels.

Not a lot of exhausts get this form of treatment but when you’re building a piece for a show car, it has to shine! Here’s a picture of the car (courtesy of the owner __dekay__ on Instagram) at the first car show it was entered in:

Most projects we supply the material for the job at hand, however we also accept customer supplied material too. Here we have some 2″ and 2.5″ SCH40 pipe dropped off and ready for processing. We had a design submitted from the customer and it is now time to get to work!

We took the customer design, modeled it in Solidworks to get an idea of weight and to help with creating coping templates for the “v” section of tubing.

Most tubing can be coped with a hole saw in a tube/pipe notcher. However with SCH40 material of this size coping it on the bandsaw is much quicker and more cost effective. Notice the c-clamp at the bottom left of the photo. This ensures a consistent cut location by allowing the tube to butt up against it prior to cutting. Repeatability just makes things so much easier and quicker.

Here’s all the tubing processed (except for the “v” sections), the ends are cleaned down to raw material to ensure a good quality area to weld to.

And here’s the final product ready to head back to the client’s shop. It will be used to drop in various pipe via forklift and then allow it to be easily banded and removed as a whole with a forklift.

Here we have a modern sign made for a local home builder cut out of 1/4″ steel. This is after it is cut, acid bathed and media blasted. It has some weight to it and is now ready for powder coating. This is the first time we’ve powder coated a part that has been previously engraved. Notice the engraving near the bottom of the part?

Here it is after having bonded silver vein powder applied to it. And the engraving disappeared…

Powder looks really good and has a slight texture to it, which is why it filled in the engraving.

So here’s the solution. Engraving and cutting a 16ga 304SS piece to be secured with the two bottom mounting holes. Looks much better!

Here we’ve got a few 304SS pieces that need welding, a few alignment marks from the customer and some tweaks are needed prior to welding.

No problem! Everything stainless steel is backpurged to ensure that there is 100% penetration and to ensure that the inside of the weld is just as protected, strong and as beautiful as the outside weld.

Miscellaneous parts needing some last minute work prior to a car show coming up. It’s not every day we can do same evening turnarounds…but in some cases we can make it happen.

All done welding. 100% backpurged as per usual. The customer only wanted the first few inches of the tubing brushed as the rest will be covered up with ceramic exhaust wrapping insulator.

The intercooler had some brackets welded on as well as another SS dump pipe having a flange welded on.

We’re always working on a variety of projects so nothing is ever dull in the shop! Here are some of the things that have been cut and built recently.

Here a customer designed a slotted welding table top which will allow for the use of clamps in various positions in and around the table. It is 3/8″ thick hot rolled 44w steel.

Nothing but the best! Our CNC table allows for high quality cutting with minimal dross. It allows for very quick clean up time which eliminates extra cost.

Here we have a Subaru external wastegate (EWG) dump that will be merging back into the downpipe. You can just slightly see the external wastegate dump to the right of the downpipe and just below the cross member.

After finishing the wastegate tubing and coping it to match up with the downpipe it is tacked in place to ensure the whole system can be removed from the car (it is very close to the front CV axle).

Now with it being removed the dump outlet is traced onto the downpipe, the tacks are broken and is ready for plasma cutting, brushing, final tacking on the car and then finish welding on the bench.

We also had a F20C (from a Honda S2000) valve cover getting ready for powdercoating. It is washed, blasted and then pre-baked. The pre-baking allows any oil in the grains of the aluminum casting to push out to the surface and be cleaned via another blasting process. Not doing this step could result in oil coming out during the powder coating curing process, and if that happens powder coating defects will occur. So cleanliness is very important.

It’s hard to see in this photo but there is actually a 4″x6″ rectangular tubing that fits just inside the valve cover to elevate it off the rack. This doesn’t matter much for the pre-baking process, however during the powder coating curing process it is. Nobody wants indentations along the bottom of their valve cover from a rack!

All threaded holes, nipples and open fittings are plugged with silicone plugs and masked with high heat tape.

The customer chosen wrinkle red powder is applied. The powder coating equipment we use varies the charge voltage to the powder particles, so it avoids the faraday cage effect. Essentially sharp corners or deep recesses will actually repel powder, so by changing the charge voltage differently charged particles will “stick” in different areas. Thus allowing for a more consistent coverage and higher quality finish in the end. Now it’s ready to go in the oven.

And here’s the final part after all the plugs and masking is removed. Nothing but the best for our clients!

Thanks for looking! If you’re interested more in our powder coating services, TIG welding or CNC cutting please click on the links. Or subscribe to the blog at the bottom right hand corner of your browser, click on the follow button. Stay tuned for another future project…

We had the pleasure of building a Ford Ranger exhaust system a little while ago. The system was all constructed from 304 stainless steel, TIG welded, backpurged and using existing holes on the frame for hanger mounts. This truck has been stripped down to the bare frame and built up with care, so this truck is as clean if not cleaner than some new vehicles we’ve worked on. The passenger side exhaust was very straightforward, but the driver’s side had an interesting header that dumped to the ground ahead of the transmission. So with the driver’s side we had to use some mandrel bends to redirect the exhaust flow around the transmission and over the sub-frame.

Here’s the Ford Ranger up on the hoist ready for the exhaust system to be built.

Here’s the system tacked up and ready for polishing.

Once all the tubes are tacked, then the tube polishing begins. This takes the raw 304 SS tubing and brings it to a #4 Architectural Finish, see more info here on our polishing page. Tube polishing can be done before or after welding, however most customers like the look/coloring of welds on stainless steel so we typically polish prior to welding. After polishing the tubing must be handled very carefully, wrapped, cannot sit on anything steel (due to embedding foreign material that could rust) or anything hard that could scratch the surface. Here you can see the polished on the left and raw material on the right.

And here is the polishing completed.

Now both tubes are tacked and polished it is time to tape all the joints and get it ready for backpurging and TIG welding. Backpurging is when the inside of the tube is filled with an inert gas, in this case Argon, this protects the backside of the weld from contamination commonly known as “sugaring”. Sugaring is an oxidized area of Chromium that combines with oxygen to form a hard thick porous oxide layer. This oxide layer depletes the Chromium content in the stainless steel near the weld and if enough is depleted the corrosion protection can be compromised. The oxide layer is porous so it leaves the inside of the weld open to corrosion and can disrupt exhaust flow. This is why backpurging is important, especially on a high quality exhaust system. Here is some prep shots prior to welding.

Here’s the exhaust system all welded up (sans hangers).

Now to install it on the truck. Here’s the tight hoop between the transmission and sub-frame.

If you have any questions or further interest please take a look at our Services Page or send us a message through our Contact Page. Thanks for looking.

Lots of things going on in the shop lately, we just haven’t had much time to bring the camera in to take some photos. We had a DSM that needed some general modifications to get it ready for dyno tuning. We had to modify the IC piping, divorced wastegate dump as well as all the flanges for the exhaust system. Here are a few quick photos of some of the welding and work that was done. Nothing major made from scratch, but instead just ironing out any little kinks to get the car ready to really perform.

First we got the car up on the hoist and began by removing the existing exhaust system, divorced wastegate dump as well as disconnecting some of the IC piping.

The Thermal Research and Development exhaust had all its two and three bolt flanges cut off and in their place would be a v-band clamps. Here’s one of them after being welded up. The entire tube assembly is put overtop the green hose (which is a back purge hose fed through the welding table) and the tin foil acts as a dam to keep the argon inside the cylinder while it’s being welded. There is a few small holes in the tin foil to allow argon to flow out to allow for a complete purge and ultimately an inert environment. The scrap tube on the bottom is to elevate the v-band assembly to keep it at a comfortable height during welding.

Here it is welded in place on the car.

Typically to prevent a silicone coupler from coming off, either end of the tubing that butts up in the coupler must be bead rolled (as seen on the left tubing) or have weld beads applied. This “hump(s)” prevents the hose clamp from sliding and ultimately having the coupler blow off the intercooler tubing. In this case the tubing on the right is actually a part of the intercooler, which is bolted up in behind the bumper. The easiest way to retain the silicone coupler is to add a few evenly spaced beads, two of the four beads required some contortion skills. These two were the easy ones.

This was one of the tricky ones, the other was welded with a mirror so it was hard to get a photo. In this case one hand through a duct in the bumper with the TIG torch, and another hand coming up underneath the car with some TIG filler.

In among working with mannequins we had a chance to do an exhaust repair and have a custom tool built. The exhaust repair was pretty straight forward, it was a crack that propagated around the merge of a stainless steel system. The quick and simple way would be to run a bead over it…however the chances of it cracking are still there since the quality of the original weld is under question hidden under a nice TIG weld. Not good. So instead we grind the weld out all the way around, then run two passes around the collector with some filler material to make it strong.

The crack was more apparent on the other side of this part.

Once the weld is ground out the surface around the weld has to be cleaned and prepped prior to welding. After that process the inside of the tubing has to be back purged with argo and then it’s ready to weld. Here it is all welded up and ready to go.

Here’s the custom tool that we made for another customer. Two 304 SS plates with a bolt and pipe passing through them. The bolt and pipe are welded to the smaller diameter plate, this allows the larger plate to be torqued down and expand the rubber gasket to seal the assembly in the pipe. The pipe is then connected to a manometer or similar pressure gauge to monitor pressure in a piping system. Perpendicularity of the bolt and pipe are important, otherwise binding would occur when torquing or disassembling the part.

We’ve been busy the last few days TIG welding and CNC cutting up a variety of materials and a variety of thicknesses for some local fabricators.

Here’s some 1/2″ 44w steel plate that we cut, the internal features were cut with the corner lockout on so it allow for a slower cutting speed and less taper. We’ve seen a huge improvement with holes!

While cutting all the half inch steel we had some room to nest a prototype rotation gauge. This tool will be used with our tubing bender to ensure that our bends are on the correct plane or what angle the plane should be. This was designed in Solidworks to be perfectly balanced left-to-right as the center of gravity is located right in the center of the “V”. It just needs a tapped hole at the bottom of the “J” for a 3/8″ bolt.

After all the heavy lifting we had a quick tweak to make with this exhaust that is destined for a Dodge Viper. The hangers were off by 1/2″ (hence the pair of black “X’s”) and needed some adjustment.

Normally we’d just cut the brackets off and just create new ones, but the customer wanted a quick fix, so instead we strategically cut the hanger, moved them to where it should be and then welded in the cuts. Made for really quick work and it provided a low cost fix.

Now onto a R32 Skyline anti-sway bar modification. We already started in this photo by cutting three of the four mounting points.

Rear anti-sway bar mount removed.

Front anti-swaybar mount removed.

With the mounts removed the ends of the tubing are prepped. Here the removed mount is having the orientation double checked with index mark on the tube.

Here are the new brackets cut off the CNC plasma table. The new mount for the front allows for an additional mounting hole 0.875″ forward and behind the stock mounting location. The rear allows for 1″ forward and behind. This will allow the driver to adjust the anti-sway bar roll stiffness and alter the handling of the car.

Checking alignment.

Tacking.

Checking the alignment on the other end.

Getting ready to tack.

Beginning to weld them all up!

Post flow. This is when the argon is purging after the arc has been extinguished. This allows for the weld to cool down in an inert atmosphere as well as the tungsten and filler rod. This all avoids contamination and yields very high quality welds.

This was a multi-pass weld so as to ensure that this joint would be strong and not fail in this high stress area.

All our jobs of the day ready to pick up and go!

UPDATE – 5-May-13

Our customer took those 1/2″ steel plates (first three photos in this post) and fabricated a hitch for a John Deere tractor.

We received a box with all the pieces required to build TIG weld this stainless steel midpipe. When you have a customer that provides parts with excellent fit-up it makes welding a breeze! All the pieces had index marks and were numbered so we knew what order to weld these pieces up and how they were orientated to each other. This midpipe is backpurged and TIG welded, we also used some Kapton tape to reduce wasting backpurge gas and to ensure no air was being brought inside the tubing.

We used some scrap rectangular tubing as spacers to keep everything nice and straight during the tacking process.

The midpipe is now ready for welding. Kapton tape is the best for sealing up tacked joints, it leaves no residue when removed, can withstand 400°C and makes anything stainless look like something from NASA. This allows for the use of less argon during backpurging which ultimately saves the customer money. Here we have all the joints taped up, and the argon is flowing inside the tubing to provide an inert atmosphere to protect the inside of the weld. After a few minutes we begin welding.

Some of the first beads. The welds look good on the outside, but also look just as good on the inside.

Welding in the O2 bung.

The stainless steel midpipe is completely done and ready to be packaged and sent back to our customer. Anything with a nice surface finish we wrap up with extra care in order to reduce the chances of any stray scratches. Repurposing towels works great for protecting the metalwork while in transit to the customer (along with shredded paper filler material).

Here we’re working on a super clean Pontiac Sunbird building a stainless steel 2.5″ dual exhaust system that splits over the rear axle. This 2.5″ dual exhaust system is 100% TIG welded and backpurged to allow for the highest quality welds.

The customer wanted to reuse the exhaust tips so one down one to go, cleaning up and polishing the old tips that have their share of scratches and road grime. We used the Baldor polisher with a sisal wheel with black emery compound for a rough cut, then a spiral sewn wheel with brown tripoli compound for a final cut. Take a look at our polishing services offered here for more info.

Here’s the backpurge setup running, one flow meter (grey hose) is for the TIG the other (green hose) is for backpurging the inside of the exhaust prior to welding.

Here’s the Mint Design backpurge jig knocked off the CNC table. It can bolt up to begin backpurging any 2.5″ exhaust system, or at least systems with the same bolt pattern. We’ll be cutting a set of flanges to allow backpurge from 2″ up to 4″ exhaust flanges.

The old muffler hangers were not the best, we ended up removing them off the car, so here are the new ones to be welded to the car. They are solid 1/2″ 304SS rod welded to a steel plate with 309 filler. the 309 filler allows for stainless steel to be welded to mild steel. The purpose for the mild steel base flange is that it’ll be MIG welded back onto the steel body of the car.

What’s not to love about twin turbo and the AWD drivetrain of the Nissan R32 Skyline? Here we are building a 304 stainless steel exhaust system that will allow this R32 Skyline to exhale with ease. Here are some progress shots of a twin 3″ merging to a 4″ exhaust system.

Using a paper template to coping the stainless steel tubing with the plasma cutter.

And after about 35′ of welding this is what is left (sans muffler).

Might not look like much, but the bracket was cut on the CNC table. Quicker and easier than doing it by hand.

The seal of approval (ACE Engineering’s previous logo).

Lightly polished SS tip welded onto the muffler

All done and mounted. Notice the subtle V-band guards cut out on the CNC table. Due to the nature of this exhaust system it sits quite low, so to mitigate any damage from speed bumps or anything snagging the V-band clamps, the guards prevent it from getting snagged and cause expensive damage.